Computer systems are comprised of a number of electronic components that must interoperate. To minimize the costs of various components, different components are made which operate at different voltages. If the output level is not compatible with an input level, the device may be damaged and interoperation thwarted.
In prior circuit design, a level shifter circuit commonly would be used to interconnect devices, for example by interconnecting sections of a bus system. Each section would have a different supply voltage and different logic level. In a typical example, each section would have a supply voltage; pull up resistors and devices connected to the supply voltage; and a serial data bus line and a serial clock bus line connected to the devices. An exemplary level shifter circuit would include a gate connected to the lower voltage supply, sources connected to the lower voltage bus lines, and drains connected to the higher voltage bus lines. One such level shifter circuit would be required for each different supply voltage.
Level shifter circuits are generally specific to specific voltage levels. Thus for each device or group of devices having a specific voltage operating level, the system requires specific circuitry to allow use of the devices.